Copolymer-type pigment dispersing agents have been developed in a variety of fields.
Pigment dispersing agents that improve, for example, the dispersibility, fluidity, storage stability, post-drying redissolution properties and substrate adhesion of pigments for ink, particularly, carbon black, have been developed. Patent Document 1 discloses a pigment composition comprising a pigment, an organic dye derivative containing an acidic functional group, an alkali-soluble resin and an organic solvent, wherein the alkali-soluble resin having an amino group and/or a quaternary ammonium group thereof has a basic equivalent of 3000 to 20000 g/eq and an acid number of 30 to 200 mgKOH/g. Specifically, the document describes a random copolymer of n-butyl methacrylate, methyl methacrylate, methacrylic acid and dimethylaminoethyl methacrylate, or the like as the alkali-soluble resin.
Since the random copolymer of n-butyl methacrylate, methyl methacrylate, methacrylic acid and dimethylaminoethyl methacrylate has various properties based on their specific structures, their development has been studied in various fields.
Patent Documents 2 and 3 focus on the amphoteric polymer properties of the random copolymer of getting positively or negatively charged by acid or base treatment, and utilize the random copolymer as an electrophoretic composition.
Alternatively, Patent Document 4 focuses on the reactivity of carboxyl and amino groups in the random copolymer and utilizes the random copolymer as a binder for silyl isocyanate.
Alternatively, Patent Document 5 discloses that the random copolymer is utilized as a powder paint composition, wherein the carboxyl group of the random copolymer is cross-linked with an epoxy group with the amino group of the random copolymer as a catalyst.